I The Shadow of a Cowl II The Pilbroch of the M'Gregors III The Scorpion's Tail IV Mademoiselle Dorian V The Sealed Envelope VI The Assistant Commissioner VII Contents of the Sealed Envelope VIII The Assistant Commissioner's Theory IX The Chinese Coin X "Close Your Shutters at Night" XI The Blue Ray

Part II

STATEMENT OF M. GASTON MAX

I. THE DANCER OF MONTMARTRE

I Zara el-Khala II Concerning the Grand Duke III A Strange Question IV The Fight in the Cafe

II. "LE BALAFRE"

I I Become Charles Malet II Baiting the Trap III Disappearance of Charles Malet IV I Meet an Old Acquaintance V Conclusion of Statement

Part III

AT THE HOUSE OF AH-FANG-FU

I The Brain Thieves II The Red Circle III Miska's Story IV Miska's Story (concluded) V The Heart of Chunda Lal VI The Man with the Scar VII In the Opium Den VIII The Green-Eyed Joss

Part IV

THE LAIR OF THE SCORPION

I The Sublime Order II The Living Death III The Fifth Secret of Rache Churan IV The Guile of the East V What Happened to Stuart VI "Jey Bhowani!" VII The Way of the Scorpion

Part I

THE COWLED MAN

CHAPTER I

THE SHADOW OF A COWL

Keppel Stuart, M.D., F. R. S., awoke with a start and discovered himself to be bathed in cold perspiration. The moonlight shone in at his window, but did not touch the bed, therefore his awakening could not be due to this cause. He lay for some time listening for any unfamiliar noise which might account for the sudden disturbance of his usually sound slumbers. In the house below nothing stirred. His windows were widely open and he could detect that vague drumming which is characteristic of midnight London; sometimes, too, the clashing of buffers upon some siding of the Brighton railway where shunting was in progress and occasional siren notes from the Thames. Otherwise—nothing.

He glanced at the luminous disk of his watch. The hour was half-past two. Dawn was not far off. The night seemed to have become almost intolerably hot, and to this heat Stuart felt disposed to ascribe both his awakening and also a feeling of uncomfortable tension of which he now became aware. He continued to listen, and, listening and hearing nothing, recognized with anger that he was frightened. A sense of some presence oppressed him. Someone or something evil was near him—perhaps in the room, veiled by the shadows. This uncanny sensation grew more and more marked.

Stuart sat up in bed, slowly and cautiously, looking all about him. He remembered to have awakened once thus in India—and to have found a great cobra coiled at his feet. His inspection revealed the presence of nothing unfamiliar, and he stepped out on to the floor.

A faint clicking sound reached his ears. He stood quite still. The clicking was repeated.

"There is someone downstairs in my study!" muttered Stuart.

He became aware that the fear which held him was such that unless he acted and acted swiftly he should become incapable of action, but he remembered that whereas the moonlight poured into the bedroom, the staircase would be in complete darkness. He walked barefooted across to the dressing-table and took up an electric torch which lay there. He had not used it for some time, and he pressed the button to learn if the torch was charged. A beam of white light shone out across the room, and at the same instant came another sound.

If it came from below or above, from the adjoining room or from

Outside in the road, Stuart knew not. But following hard upon the mysterious disturbance which had aroused him it seemed to pour ice into his veins, it added the complementary touch to his panic. For it was a kind of low wail—a ghostly minor wail in falling cadences—unlike any sound he had heard. It was so excessively horrible that it produced a curious effect.

Discovering from the dancing of the torch-ray that his hand was trembling, Stuart concluded that he had awakened from a nightmare and that this fiendish wailing was no more than an unusually delayed aftermath of the imaginary horrors which had bathed him in cold perspiration.

He walked resolutely to the door, threw it open and cast the beam of light on to the staircase. Softly he began to descend. Before the study door he paused. There was no sound. He threw open the door, directing the torch-ray into the room.

Cutting a white lane through the blackness, it shone fully upon his writing-table, which was a rather fine Jacobean piece having a sort of quaint bureau superstructure containing cabinets and drawers. He could detect nothing unusual in the appearance of the littered table. A tobacco jar stood there, a pipe resting in the lid. Papers and books were scattered untidily as he had left them, surrounding a tray full of pipe and cigarette ash. Then, suddenly, he saw something else.

One of the bureau drawers was half opened.

Stuart stood quite still, staring at the table. There was no sound in the room. He crossed slowly, moving the light from right to left. His papers had been overhauled methodically. The drawers had been replaced, but he felt assured that all had been examined. The light switch was immediately beside the outer door, and Stuart walked over to it and switched on both lamps. Turning, he surveyed the brilliantly illuminated room. Save for himself, it was empty. He looked out into the hallway again. There was no one there. No sound broke the stillness. But that consciousness of some near presence asserted itself persistently and uncannily.

"My nerves are out of order!" he muttered. "No one has touched my papers. I must have left the drawer open myself."

He switched off the light and walked across to the door. He had actually passed out intending to return to his room, when he became aware of a slight draught. He stopped.

Someone or something, evil and watchful, seemed to be very near again. Stuart turned and found himself gazing fearfully in the direction of the open study door. He became persuaded anew that someone was hiding there, and snatching up an ash stick which lay upon a chair in the hall he returned to the door. One step into the room he took and paused—palsied with a sudden fear which exceeded anything he had known.

A white casement curtain was drawn across the French windows ... and outlined upon this moon-bright screen he saw a tall figure. It was that of a cowled man!

Such an apparition would have been sufficiently alarming had the cowl been that of a monk, but the outline of this phantom being suggested that of one of the Misericordia brethren or the costume worn of old by the familiars of the Inquisition!

His heart leapt wildly, and seemed to grow still. He sought to cry out in his terror, but only emitted a dry gasping sound.

The psychology of panic is obscure and has been but imperfectly explored. The presence of the terrible cowled figure afforded a confirmation of Stuart's theory that he was the victim of a species of waking nightmare.

Even as he looked, the shadow of the cowled man moved—and was gone.

Stuart ran across the room, jerked open the curtains and stared out across the moon-bathed lawn, its prospect terminated by high privet hedges. One of the French windows was wide open. There was no one on the lawn; there was no sound.

"Mrs. M'Gregor swears that I always forget to shut these windows at night!" he muttered.

He closed and bolted the window, stood for a moment looking out across the empty lawn, then turned and went out of the room.

CHAPTER II

THE PIBROCH OF THE M'GREGORS

Dr. Stuart awoke in the morning and tried to recall what had occurred during the night. He consulted his watch and found the hour to be six a. m. No one was stirring in the house, and he rose and put on a bath robe. He felt perfectly well and could detect no symptoms of nervous disorder. Bright sunlight was streaming into the room, and he went out on to the landing, fastening the cord of his gown as he descended the stairs.

His study door was locked, with the key outside. He remembered having locked it. Opening it, he entered and looked about him. He was vaguely disappointed. Save for the untidy litter of papers upon the table, the study was as he had left it on retiring. If he could believe the evidence of his senses, nothing had been disturbed.

Not content with a casual inspection, he particularly examined those papers which, in his dream adventure, he had believed to have been submitted to mysterious inspection. They showed no signs of having been touched. The casement curtains were drawn across the recess formed by the French windows, and sunlight streamed in where, silhouetted against the pallid illumination of the moon, he had seen the man in the cowl. Drawing back the curtains, he examined the window fastenings. They were secure. If the window had really been open in the night, he must have left it so himself.

"Well," muttered Stuart—"of all the amazing nightmares!"

He determined, immediately he had bathed and completed his toilet, to write an account of the dream for the Psychical Research Society, in whose work he was interested. Half an hour later, as the movements of an awakened household began to proclaim themselves, he sat down at his writing-table and commenced to write.

Keppel Stuart was a dark, good-looking man of about thirty-two, an easy-going bachelor who, whilst not over ambitious, was nevertheless a brilliant physician. He had worked for the Liverpool School of Tropical Medicine and had spent several years in India studying snake poisons. His purchase of this humdrum suburban practice had been dictated by a desire to make a home for a girl who at the eleventh hour had declined to share it. Two years had elapsed since then, but the shadow still lay upon Stuart's life, its influence being revealed in a certain apathy, almost indifference, which characterised his professional conduct.

His account of the dream completed, he put the paper into a pigeon-hole and forgot all about the matter. That day seemed to be more than usually dull and the hours to drag wearily on. He was conscious of a sort of suspense. He was waiting for something, or for someone. He did not choose to analyse this mental condition. Had he done so, the explanation was simple—and one that he dared not face.

At about ten o'clock that night, having been called out to a case, he returned to his house, walking straight into the study as was his custom and casting a light Burberry with a soft hat upon the sofa beside his stick and bag. The lamps were lighted, and the book-lined room, indicative of a studious and not over-wealthy bachelor, looked cheerful enough with the firelight dancing on the furniture.

Mrs. M'Gregor, a grey-haired Scotch lady, attired with scrupulous neatness, was tending the fire at the moment, and hearing Stuart come in she turned and glanced at him.

"A fire is rather superfluous to-night, Mrs. M'Gregor," he said. "I found it unpleasantly warm walking."

"May is a fearsome treacherous month, Mr. Keppel," replied the old housekeeper, who from long association with the struggling practitioner had come to regard him as a son. "An' a wheen o' dry logs is worth a barrel o' pheesic. To which I would add that if ye're hintin' it's time ye shed ye're woolsies for ye're summer wear, all I have to reply is that I hope sincerely ye're patients are more prudent than yoursel'."

She placed his slippers in the fender and took up the hat, stick and coat from the sofa. Stuart laughed.

"Most of the neighbors exhibit their wisdom by refraining from becoming patients of mine, Mrs. M'Gregor."

"That's no weesdom; it's just preejudice." "Prejudice!" cried Stuart, dropping down upon the sofa.

"Aye," replied Mrs. M'Gregor firmly—"preejudice! They're no' that daft but they're well aware o' who's the cleverest physeecian in the deestrict, an' they come to nane other than Dr. Keppel Stuart when they're sair sick and think they're dying; but ye'll never establish the practice you desairve, Mr. Keppel—never—until—"

"Until when, Mrs. M'Gregor?"

"Until ye take heed of an auld wife's advice and find a new housekeeper."

"Thirty years come last Shrove Tuesday; I dandled ye on my knee, and eh! but ye were bonny! God forbid, but I'd like to see ye thriving as ye desairve, and that ye'll never do whilst ye're a bachelor."

"Oh!" cried Stuart, laughing again—"oh, that's it, is it? So you would like me to find some poor inoffensive girl to share my struggles?"

Mrs. M'Gregor nodded wisely. "She'd have nane so many to share. I know ye think I'm old-fashioned, Mr. Keppel and it may be I am; but I do assure you I would be sair harassed, if stricken to my bed—which, please God, I won't be—to receive the veesits of a pairsonable young bachelor—"

"Er—Mrs. M'Gregor!" interrupted Stuart, coughing in mock rebuke—"quite so! I fancy we have discussed this point before, and as you say your ideas are a wee bit, just a wee bit, behind the times. On this particular point I mean. But I am very grateful to you, very sincerely grateful, for your disinterested kindness; and if ever I should follow your advice——"

Mrs. M'Gregor interrupted him, pointing to his boots. "Ye're no' that daft as to sit in wet boots?"

"Really they are perfectly dry. Except for a light shower this evening, there has been no rain for several days. However, I may as well, since I shall not be going out again."

He began to unlace his boots as Mrs. M'Gregor pulled the white casement curtains across the windows and then prepared to retire. Her hand upon the door knob, she turned again to Stuart.

"The foreign lady called half an hour since, Mr. Keppel."

Stuart desisted from unlacing his boots and looked up with lively interest. "Mlle. Dorian! Did she leave any message?"

"Really, I am sorry I was detained," declared Stuart, replacing his boot. "How long has she been gone, then?"

"Just the now. No more than two or three minutes. I trust she is no worse."

"Worse!"

"The lass seemed o'er anxious to see you."

"Well, you know, Mrs. M'Gregor, she comes a considerable distance."

"So I am given to understand, Mr. Keppel," replied the old lady; "and in a grand luxurious car."

Stuart assumed an expression of perplexity to hide his embarrassment. "Mrs. M'Gregor," he said rather ruefully, "you watch over me as tenderly as my own mother would have done. I have observed a certain restraint in your manner whenever you have had occasion to refer to Mlle. Dorian. In what way does she differ from my other lady patients?" And even as he spoke the words he knew in his heart that she differed from every other woman in the world.

"Now, Mr. Keppel, laddie, ye're angry with me, and like enough I am a meddlesome auld woman. But I know what a man will do for shining een and a winsome face—nane better to my sorrow—and twa times have I heard the Warning."

Stuart stood up in real perplexity. "Pardon my density, Mrs. M'Gregor, but—er—the Warning? To what 'warning' do you refer?"

Seating herself in the chair before the writing-table, Mrs. M'Gregor shook her head pensively. "What would it be," she said softly, "but the Pibroch o' the M'Gregors?"

Stuart came across and leaned upon a corner of the table. "The Pibroch of the M'Gregors?" he repeated.

"Nane other. 'Tis said to be Rob Roy's ain piper that gives warning when danger threatens ane o' the M'Gregors or any they love."

"As well as I hear you now, laddie, I heard the pibroch on the day a certain woman first crossed my threshold, nigh thirty years ago, in Inverary. And as plainly as I heard it wailing then, I heard it the first evening that Miss Dorian came to this house!"

Torn between good-humoured amusement and real interest, "If I remember rightly," said Stuart, "Mlle. Dorian first called here just a week ago, and immediately before I returned from an Infirmary case?"

"Your memory is guid, Mr. Keppel."

"And when, exactly, did you hear this Warning?"

"Twa minutes before you entered the house; and I heard it again the now."

"What! you heard it to-night?"

"I heard it again just the now and I lookit out the window."

"Did you obtain a glimpse of Rob Roy's piper?"

"Ye're laughing at an old wife, laddie. No, but I saw Miss Dorian away in her car and twa minutes later I saw yourself coming round the corner."

"If she had only waited another two minutes," murmured Stuart. "No matter; she may return. And are these the only occasions upon which you have heard this mysterious sound, Mrs. M'Gregor?"

"No, Master Keppel, they are not. I assure ye something threatens. It wakened me up in the wee sma' hours last night—the piping—an' I lay awake shaking for long eno'."

"How extraordinary. Are you sure your imagination is not playing you tricks?"

"Ah, you're no' takin' me seriously, laddie."

"Mrs. M'Gregor"—he leaned across the table and rested his hands upon her shoulders—"you are a second mother to me, your care makes me feel like a boy again; and in these grey days it's good to feel like a boy again. You think I am laughing at you, but I'm not. The strange tradition of your family is associated with a tragedy in your life; therefore I respect it. But have no fear with regard to Mlle. Dorian. In the first place she is a patient; in the second—I am merely a penniless suburban practitioner. Good-night, Mrs. M'Gregor. Don't think of waiting up. Tell Mary to show Mademoiselle in here directly she arrives—that is if she really returns."

Mrs. M'Gregor stood up and walked slowly to the door. "I'll show Mademoiselle in mysel', Mr. Keppel," she said,—"and show her out."

She closed the door very quietly.

CHAPTER III

THE SCORPION'S TAIL

Seating himself at the writing-table, Stuart began mechanically to arrange his papers. Then from the tobacco jar he loaded his pipe, but his manner remained abstracted. Yet he was not thinking of the phantom piper but of Mlle. Dorian.

Until he had met this bewilderingly pretty woman he had thought that his heart was for evermore proof against the glances of bright eyes. Mademoiselle had disillusioned him. She was the most fragrantly lovely creature he had ever met, and never for one waking moment since her first visit, had he succeeded in driving her bewitching image from his mind. He had tried to laugh at his own folly, then had grown angry with himself, but finally had settled down to a dismayed acceptance of a wild infatuation.

He had no idea who Mlle. Dorian was; he did not even know her exact nationality, but he strongly suspected there was a strain of Eastern blood in her veins. Although she was quite young, apparently little more than twenty years of age, she dressed like a woman of unlimited means, and although all her visits had been at night he had had glimpses of the big car which had aroused Mrs. M'Gregor's displeasure.

Yes—so ran his musings, as, pipe in mouth, he rested his chin in his hands and stared grimly into the fire—she had always come at night and always alone. He had supposed her to be a Frenchwoman, but an unmarried French girl of good family does not make late calls, even upon a medical man, unattended. Had he perchance unwittingly made himself a party to the escapade of some unruly member of a noble family? From the first he had shrewdly suspected the ailments of Mlle. Dorian to be imaginary—Mlle. Dorian? It was an odd name.

"I shall be imagining she is a disguised princess if I wonder about her any more!" he muttered angrily.

Detecting himself in the act of heaving a weary sigh, he coughed in self-reproval and reached into a pigeon-hole for the MS. of his unfinished paper on "Snake Poisons and Their Antidotes." By chance he pulled out the brief account, written the same morning, of his uncanny experience during the night. He read it through reflectively.

It was incomplete. A certain mental haziness which he had noted upon awakening had in some way obscured the facts. His memory of the dream had been imperfect. Even now, whilst recognizing that some feature of the experience was missing from his written account, he could not identify the omission. But one memory arose starkly before him—that of the cowled man who had stood behind the curtains. It had power to chill him yet. The old incredulity returned and methodically he re-examined the contents of some of the table drawers. Ere long, however, he desisted impatiently.

"What the devil could a penniless doctor have hidden in his desk that was worth stealing!" he said aloud. "I must avoid cold salmon and cucumber in future."

He tossed the statement aside and turned to his scientific paper.

There came knock at the door.

"Come in!" snapped Stuart irritably; but the next moment he had turned, eager-eyed to the servant who had entered.

"Inspector Dunbar has called, sir."

"Oh, all right," said Stuart, repressing another sigh. "Show him in here."

There entered, shortly, a man of unusual height, a man gaunt and square both of figure and of face. He wore his clothes and his hair untidily. He was iron grey and a grim mouth was ill concealed by the wiry moustache. The most notable features of a striking face were the tawny leonine eyes, which could be fierce, which could be pensive and which were often kindly.

"Good evening, doctor," he said—and his voice was pleasant and unexpectedly light in tome. "Hope I don't intrude."

"Not at all, Inspector," Stuart assured him.

"Make yourself comfortable in the armchair and fill your pipe."

"Thanks," said Dunbar. "I will." He took out his pipe and reached out a long arm for the tobacco jar. "I came to see if you could give me a tip on a matter that has cropped up."

"Something in my line?" asked Stuart, a keen professional look coming momentarily into his eyes.

"It's supposed to be a poison case, although I can't see it myself," answered the detective—to whom Keppel Stuart's unusual knowledge of poisons had been of service in the past; "but if what I suspect is true, it's a very big case all the same."

Laying down his pipe, which he had filled but not lighted, Inspector Dunbar pulled out from the inside pocket of his tweed coat a bulging note-book and extracted therefrom some small object wrapped up in tissue paper. Unwrapping this object, he laid it upon the table.

"Tell me what that is, doctor," he said, "and I shall be obliged."

Stuart peered closely at that which lay before him. It was a piece of curiously shaped gold, cunningly engraved in a most unusual way. Rather less than an inch in length, it formed a crescent made up of six oval segments joined one to another, the sixth terminating in a curled point. The first and largest segment ended jaggedly where it had evidently been snapped off from the rest of the ornament—if the thing had formed part of an ornament. Stuart looked up, frowning in a puzzled way.

"It is a most curious fragment of jewellery—possibly of Indian origin," he said.

Inspector Dunbar lighted his pipe and tossed the match-end into the fire. "But what does it represent?" he asked.

"Oh, as to that—I said a curious fragment advisedly, because I cannot imagine any woman wearing such a beastly thing. It is the tail of a scorpion."

"Ah!" cried Dunbar, the tawny eyes glittering with excitement. "The tail of a scorpion! I thought so! And Sowerby would have it that it represented the stem of a Cactus or Prickly Pear!"

"Not so bad a guess," replied Stuart. "There are resemblances—not in the originals but in such a miniature reproduction as this. He was wrong, however. May I ask where you obtained the fragment?"

"I'm here to tell you, doctor, for now that I know it's a scorpion's tail I know that I'm out of my depth as well. You've travelled in the East and lived in the East—two very different things. Now, while you were out there, in India, China, Burma, and so on, did you ever come across a religion or a cult that worshipped scorpions?"

Stuart frowned thoughtfully, rubbing his chin with the mouthpiece of his pipe. Dunbar watched him expectantly.

Inspector Dunbar nodded, stood up and crossed the room, where he busied himself with syphon and decanter. Presently he returned, carrying two full glasses, one of which he set before Stuart. "What's the answer, doctor?" he asked.

"The answer is no. I am not acquainted with any sect of scorpion-worshippers, Inspector. But I once met with a curious experience at Su-Chow in China, which I have never been able to explain, but which may interest you. It wanted but a few minutes to sunset, and I was anxious to get back to my quarters before dusk fell. Therefore I hurried up my boy, who was drawing the rickshaw, telling him to cross the Canal by the Wu-men Bridge. He ran fleetly in that direction, and we were actually come to the steep acclivity of the bridge, when suddenly the boy dropped the shafts and fell down on his knees, hiding his face in his hands.

"I stared down at him in amazement, as was natural, and not a little angrily; for his sudden action had almost pitched me on my head. But there he crouched, immovable, and staring up the slope I say that it was entirely deserted except for one strange figure at that moment crossing the crown of the bridge and approaching. It was the figure of a tall and dignified Chinaman, or of one who wore the dress of a Chinaman. For the extra-ordinary thing about the stranger's appearance was this; he also wore a thick green veil!"

"Covering his face?"

"So as to cover his face completely. I was staring at him in wonder, when the boy, seeming to divine the other's approach, whispered, 'Turn your head away! Turn your head away!"

"He was referring to the man with the veil?"

"Undoubtedly. Of course I did nothing of the kind, but it was impossible to discern the stranger's features through the thick gauze, although he passed quite close to me. He had not proceeded another three paces, I should think, before my boy had snatched up the shafts and darted across the bridge as though all hell were after him! Here's the odd thing, though; I could never induce him to speak a word on the subject afterwards! I bullied him and bribed him, but all to no purpose. And although I must have asked more than a hundred Chinamen in every station of society from mandarin to mendicant, 'Who or what is The Scorpion?' one and all looked stupid, blandly assuring me that they did not know what I meant."

"H'm!" said Dunbar, "it's a queer yarn, certainly. How long ago would that be, doctor?"

"Roughly—five years."

"It sounds as though it might belong to the case. Some months back, early in the winter, we received instructions at the Yard to look out everywhere in the press, in buffets, theatres, but particularly in criminal quarters, for any reference (of any kind whatever) to a scorpion. I was so puzzled that I saw the Commissioner about it, and he could tell me next to nothing. He said the word had come through from Paris, but that Paris seemed to know no more about it than we did. It was associated in some way with the sudden deaths of several notable public men about that time; but as there was no evidence of foul play in any of the cases, I couldn't see what it meant at all. Then, six weeks ago, Sir Frank Narcombe, the surgeon, fell dead in the foyer of a West-End theatre—you remember?"

CHAPTER IV

MADEMOISELLE DORIAN

The telephone bell rang.

Stuart reached across for the instrument and raised the receiver. "Yes," he said—"Dr. Stuart speaking. Inspector Dunbar is here. Hold on."

He passed the instrument to Dunbar, who had stood up on hearing his name mentioned. "Sergeant Sowerby at Scotland Yard wishes to speak to you, Inspector."

"Hullo," said Dunbar—"that you, Sowerby. Yes—but I arrived here only a short time ago. What's that?—Max? Good God! what does it all mean! Are you sure of the number—49685? Poor chap—he should have worked with us instead of going off alone like that. But he was always given to that sort of thing. Wait for me. I'll be with you in a few minutes. I can get a taxi. And, Sowerby—listen! It's 'The Scorpion' case right enough. That bit of gold found on the dead man is not a cactus stem; it's a scorpion's tail!"

He put down the telephone and turned to Stuart, who had been listening to the words with growing concern. Dunbar struck his open palm down on to the table with a violent gesture.

"We have been asleep!" he exclaimed. "Gaston Max of the Paris Service has been at work in London for a month, and we didn't know it!"

"Gaston Max!" cried Start—"then it must be a big case indeed."

As a student of criminology the name of the celebrated Frenchman was familiar to him as that of the foremost criminal investigator in Europe, and he found himself staring at the fragment of gold with a new and keener interest.

"Poor chap," continued Dunbar—"it was his last. The body brought in from Hanover Hole has been identified as his."

"What! it is the body of Gaston Max!"

"Paris has just wired that Max's reports ceased over a week ago. He was working on the case of Sir Frank Narcombe, it seems, and I never knew! But I predicted a long time ago that Max would play the lone-hand game once too often. They sent particulars. The identification disk is his. Oh! there's no doubt about it, unfortunately. The dead man's face is unrecognizable, but it's not likely there are two disks of that sort bearing the initials G.M. and the number 49685. I'm going along now. Should you care to come, doctor?"

"I am expecting a patient, Inspector," replied Stuart—"er—a special case. But I hope you will keep me in touch with this affair?"

"Well, I shouldn't have suggested your coming to the Yard if I hadn't wanted to do that. As a matter of fact, this scorpion job seems to resolve itself into a case of elaborate assassination by means of some unknown poison; and although I should have come to see you in any event, because you have helped me more than once, I came to-night at the suggestion of the Commissioner. He instructed me to retain your services if they were available."

"If he was right," said Dunbar, taking up the piece of gold from the table, "what was Gaston Max doing with this thing in his possession?"

"There may be no earthly connection between Max's inquiries and the death of Sir Frank."

"On the other hand—there may! Leaving Dr. Halesowen out of the question, are you open to act as expert adviser in this case?"

"Certainly; delighted."

"Your fee is your own affair, doctor. I will communicate with you later, if you wish, or call again in the morning."

Dunbar wrapped up the scorpion's tail in the piece of tissue paper and was about to replace it in his note-case. Then:

"I'll leave this with you, doctor," he said. "I know it will be safe enough, and you might like to examine it at greater leisure."

"Very well," replied Stuart. "Some of the engraving is very minute. I will have a look at it through a glass later."

He took the fragment from Dunbar, who had again unwrapped it, and, opening a drawer of the writing-table in which he kept his cheque-book and some few other personal valuables, he placed the curious piece of gold-work within and relocked the drawer.

"I will walk as far as the cab-rank with you," he said, finding himself to be possessed of a spirit of unrest. Whereupon the two went out of the room, Stuart extinguishing the lamps as he came to the door.

They had not left the study for more than two minutes ere a car drew up outside the house, and Mrs. M'Gregor ushered a lady into the room but lately quitted by Stuart and Dunbar, turning up the lights as she entered.

"The doctor has gone out but just now, Miss Dorian," she said stiffly. "I am sorry that ye are so unfortunate in your veesits. But I know he'll be no more than a few minutes."

The girl addressed was of a type fully to account for the misgivings of the shrewd old Scotswoman. She had the slim beauty of the East allied to the elegance of the West. Her features, whilst cast in a charming European mould, at the same time suggested in some subtle way the Oriental. She had the long, almond-shaped eyes of the Egyptian, and her hair, which she wore unconventionally in a picturesque fashion reminiscent of the harem, was inclined to be "fuzzy," but gleamed with coppery tints where the light touched its waves.

She wore a cloak of purple velvet having a hooded collar of white fox fur; it fastened with golden cords. Beneath it was a white and gold robe, cut with classic simplicity of line and confined at the waist by an ornate Eastern girdle. White stockings and dull gold shoes exhibited to advantage her charming little feet and slim ankles, and she carried a handbag of Indian beadwork. Mlle. Dorian was a figure calculated to fire the imagination of any man and to linger long and sweetly in the memory.

Mrs. M'Gregor, palpably ill at ease, conducted her to an armchair.

"You are very good," said the visitor, speaking with a certain hesitancy and with a slight accent most musical and fascinating. "I wait a while if I may."

"Dear, dear," muttered Mrs. M'Gregor, beginning to poke the fire, "he has let the fire down, of course! Is it out? No ... I see a wee sparkie!"

She set the poker upright before the nearly extinguished fire and turned triumphantly to Mlle. Dorian, who was watching her with a slight smile.

"That will be a comforting blaze in a few minutes, Miss Dorian," she said, and went towards the door.

"If you please," called the girl, detaining her—"do you permit me to speak on the telephone a moment? As Dr. Stuart is not at home, I must explain that I wait for him."

"Certainly, Miss Dorian," replied Mrs. M'Gregor; "use the telephone by all means. But I think the doctor will be back any moment now."

"Thank you so much."

Mrs. M'Gregor went out, not without a final backward glance at the elegant figure in the armchair. Mlle. Dorian was seated, her chin resting in her hand and her elbow upon the arm of the chair, gazing into the smoke arising from the nearly extinguished ember of the fire. The door closed, and Mrs. M'Gregor's footsteps could be heard receding along the corridor.

Mlle. Dorian sprang from the chair and took out of her handbag a number of small keys attached to a ring. Furtively she crossed the room, all the time listening intently, and cast her cloak over the back of the chair which was placed before the writing-table. Her robe of white and gold clung to her shapely figure as she bent over the table and tried three of the keys in the lock of the drawer which contained Stuart's cheque-book and in which he had recently placed the mysterious gold ornament. The third key fitted the lock, and Mlle. Dorian pulled open the drawer. She discovered first the cheque-book and next a private account-book; then from under the latter she drew out a foolscap envelope sealed with red wax and bearing, in Stuart's handwriting, the address:

She uttered a subdued exclamation; then, as a spark of light gleamed within the open drawer, she gazed as if stupefied at the little ornament which she had suddenly perceived lying near the cheque-book. She picked it up and stared at it aghast. A moment she hesitated; then, laying down the fragment of gold and also the long envelope upon the table, she took up the telephone. Keeping her eyes fixed upon the closed door of the study, she asked for the number East 89512, and whilst she waited for the connection continued that nervous watching and listening. Suddenly she began to speak, in a low voice.

"Yes! ... Miska speaks. Listen! One of the new keys—it fits. I have the envelope. But, also in the same drawer, I find a part of a broken gold 'agrab (scorpion). Yes, it is broken. It must be they find it, on him." Her manner grew more and more agitated. "Shall I bring it? The envelope it is very large. I do not know if——"

From somewhere outside the house came a low, wailing cry—a cry which Stuart, if he had heard it, must have recognized to be identical with that which he had heard in the night—but which he had forgotten to record in his written account.

"Ah!" whispered the girl—"there is the signal! It is the doctor who returns." She listened eagerly, fearfully, to the voice which spoke over the wires. "Yes—yes!"

Always glancing toward the door, she put down the instrument, took up the long envelope and paused for a moment, thinking that she had heard the sound of approaching footsteps. She exhibited signs of nervous indecision, tried to thrust the envelope into her little bag and realized that even folded it would not fit so as to escape observation. She ran across to the grate and dropped the envelope upon the smouldering fire. As she did so, the nicely balanced poker fell with a clatter upon the tiled hearth.

She started wildly, ran back to the table, took up the broken ornament and was about to thrust it into the open drawer, when the study door was flung open and Stuart came in.

CHAPTER V

THE SEALED ENVELOPE

"MADEMOISELLE DORIAN!" cried Stuart joyously, advancing with outstretched hand. She leaned back against the table watching him—and suddenly he perceived the open drawer. He stopped. His expression changed to one of surprise and anger, and the girl's slim fingers convulsively clutched the table edge as she confronted him. Her exquisite colour fled and left her pallid, dark-eyed and dismayed.

"So," he said bitterly—"I returned none too soon, Mlle.—Dorian"

"Oh! she whispered, and shrank from him as he approached nearer.

"Your object in selecting an obscure practitioner for your medical adviser becomes painfully evident to me. Diagnosis of your case would have been much more easy if I had associated your symptoms with the presence in my table drawer of"—he hesitated—"of something which you have taken out. Give me whatever you have stolen and compose yourself to await the arrival of the police."

He was cruel in his disillusionment. Here lay the explanation of his romance; here was his disguised princess—a common thief! She stared at him wildly.

"Nothing—see." She cast the little gold ornament on the table. "I look at this, but I do not mean to steal it."

She raised her beautiful eyes to his face again, and he found himself wavering. That she had made his acquaintance in order to steal the fragment of the golden scorpion was impossible, for he had not possessed it at the time of her first visit. He was hopelessly mystified and utterly miserable.

"How did you open the drawer?" he asked sternly.

She took up the bunch of keys which lay upon the table and naively exhibited that which fitted the lock of the drawer. Her hands were shaking.

"Where did you obtain this key; and why?"

She watched him intently, her lips trembling and her eyes wells of sorrow into which he could not gaze unmoved.

"If I tell you—will you let me go?"

"I shall make no promises, for I can believe nothing that you may tell me. You gained my confidence by a lie—and now, by another lie, you seem to think that you can induce me to overlook a deliberate attempt at burglary—common burglary." He clenched his hands. "Heavens! I could never have believed it of you!"

She flinched as though from a blow and regarded him pitifully as he stood, head averted.

"Oh, please listen to me," she whispered. "At first I tell you a lie, yes."

"And now?"

"Now—I tell you the truth."

"That you are a petty thief?"

"Ah! you are cruel—you have no pity! You judge me as you judge—one of your Englishwomen. Perhaps I cannot help what I do. In the East a woman is a chattel and has no will of her own."

"A chattel!" cried Stuart scornfully. "Your resemblance to the 'chattels' of the East is a remote one. There is Eastern blood in your veins, no doubt, but you are educated, you are a linguist, you know the world. Right and wrong are recognizable to the lowest savage."

"And if they recognize, but are helpless?"

Stuart made a gesture of impatience.

"You are simply seeking to enlist my sympathy," he said bitterly. "But you have said nothing which inclines me to listen to you any longer. Apart from the shock of finding you to be—what you are, I am utterly mystified as to your object. I am a poor man. The entire contents of my house would fetch only a few hundred pounds if sold to-morrow. Yet you risk your liberty to rifle my bureau. For the last time—what have you taken from that drawer?"

She leaned back against the table, toying with the broken piece of gold and glancing down at it as she did so. Her long lashes cast shadows below her eyes, and a hint of colour was returning to her cheeks. Stuart studied her attentively—even delightedly, for all her shortcomings, and knew in his heart that he could never give her in charge of the police. More and more the wonder of it all grew upon him, and now he suddenly found himself thinking of the unexplained incident of the previous night.

"You do not answer," he said. "I will ask you another question: have you attempted to open that drawer prior to this evening?"

Mlle. Dorian looked up rapidly, and her cheeks, which had been pale, now flushed rosily.

"I try twice before," she confessed, "and cannot open it."

"Ah! And—has someone else tried also?"

Instantly her colour fled again, and she stared at him wide-eyed, fearful.

"Someone else?" she whispered.

"Yes—someone else. A man ... wearing a sort of cowl——"

"Oh?" she cried and threw out her hands in entreaty. "Do not ask me of him! I dare not answer—I dare not!"

"You have answered," said Stuart, in a voice unlike his own; for a horrified amazement was creeping upon him and supplanting the contemptuous anger which the discovery of this beautiful girl engaged in pilfering his poor belongings had at first aroused.

The mystery of her operations was explained—explained by a deeper and a darker mystery. The horror of the night had been no dream but an almost incredible reality. He now saw before him an agent of the man in the cowl; he perceived that he was in some way entangled in an affair vastly more complex and sinister than a case of petty larceny.

"Has the golden scorpion anything to do with the matter?" he demanded abruptly.

And in the eyes of his beautiful captive he read the answer. She flinched again as she had done when he had taunted her with being a thief; but he pressed his advantage remorselessly.

"So you were concerned in the death of Sir Frank Narcombe!" he said.

"I was not!" she cried at him fiercely, and her widely opened eyes were magnificent. "Sir Frank Narcombe is——"

She faltered—and ceased speaking, biting her lip which had become tremulous again.

"Sir Frank Narcombe is?" prompted Stuart, feeling himself to stand upon the brink of a revelation.

"I know nothing of him—this Sir Frank Narcombe."

Stuart laughed unmirthfully.

"Am I, by any chance, in danger of sharing the fate of that distinguished surgeon?" he asked.

His question produced an unforeseen effect. Mlle. Dorian suddenly rested her jewelled hands upon his shoulders, and he found himself looking hungrily into those wonderful Eastern eyes.

"If I swear that I speak the truth, will you believe me?" she whispered, and her fingers closed convulsively upon his shoulders.

He was shaken. Her near presence was intoxicating. "Perhaps," he said unsteadily.

"Listen, then. Now you are in danger, yes. Before, you were not, but now you must be very careful. Oh! indeed, indeed, I tell you true! I tell you for your own sake. Do with me what you please. I do not care. It does not matter. You ask me why I come here. I tell you that also. I come for what is in the long envelope—look, I cannot hide it. It is on the fire!"

Stuart turned and glanced toward the grate. A faint wisp of brown smoke was arising from a long white envelope which lay there. Had the fire been actually burning, it must long ago have been destroyed. More than ever mystified, for the significance of the envelope was not evident to him, he ran to the grate and plucked the smouldering paper from the embers.

As he did so, the girl, with one quick glance in his direction, snatched her cloak, keys and bag and ran from the room. Stuart heard the door close, and racing back to the table he placed the slightly charred envelope there beside the fragment of gold and leapt to the door.

"Damn!" he said.

His escaped prisoner had turned the key on the outside. He was locked in his own study!

Momentarily nonplussed, he stood looking at the closed door. The sound of a restarted motor from outside the house spurred him to action. He switched off the lamps, crossed the darkened room and drew back the curtain, throwing open the French windows. Brilliant moonlight bathed the little lawn with its bordering of high privet hedges. Stuart ran out as the sound of the receding car reached his ears. By the time that he had reached the front of the house the street was vacant from end to end. He walked up the steps to the front door, which he unfastened with his latch-key. As he entered the hall, Mrs. M'Gregor appeared from her room.

"I did no' hear ye go out with Miss Dorian," she said.

"That's quite possible, Mrs. M'Gregor, but she has gone, you see."

"Now tell me, Mr. Keppel, did ye or did ye no' hear the wail o' the pibroch the night?

"No—I am afraid I cannot say that I did, Mrs. M'Gregor," replied Stuart patiently. "I feel sure you must be very tired and you can justifiably turn in now. I am expecting no other visitor. Good-night."

Palpably dissatisfied and ill at ease, Mrs. M'Gregor turned away.

"Good-night, Mr. Keppel," she said.

Stuart, no longer able to control his impatience, hurried to the study door, unlocked it and entered. Turning on the light, he crossed and hastily drew the curtains over the window recess, but without troubling to close the window which he had opened. Then he returned to the writing-table and took up the sealed envelope whose presence in his bureau was clearly responsible for the singular visitation of the cowled man and for the coming of the lovely Mlle. Dorian.

The "pibroch of the M'Gregors": He remembered something—something which, unaccountably, he hitherto had failed to recall: that fearful wailing in the night—which had heralded the coming of the cowled man!—or had it been a signal of some kind?

He stared at the envelope blankly, then laid it down and stood looking for some time at the golden scorpion's tail. Finally, his hands resting upon the table, he found that almost unconsciously he had been listening—listening to the dim night sounds of London and to the vague stirrings within the house.

"Now, you are in danger. Before, you were not...."

Could he believe her? If in naught else, in this at least surely she had been sincere? Stuart started—then laughed grimly.

A clock on the mantel-piece had chimed the half-hour.

CHAPTER VI

THE ASSISTANT COMMISSIONER

Detective-Inspector Dunbar arrived at New Scotland Yard in a veritable fever of excitement. Jumping out of the cab he ran into the building and without troubling the man in charge of the lift went straight on upstairs to his room. He found it to be in darkness and switched on the green-shaded lamp which was suspended above the table. Its light revealed a bare apartment having distempered walls severely decorated by an etching of a former and unbeautiful Commissioner. The blinds were drawn. A plain, heavy deal table (bearing a blotting-pad, a pewter ink-pot, several pens and a telephone), together with three uncomfortable chairs, alone broke the expanse of highly polished floor. Dunbar glanced at the table and then stood undecided in the middle of the bare room, tapping his small, widely separated teeth with a pencil which he had absently drawn from his waistcoat pocket. He rang the bell.

A constable came in almost immediately and stood waiting just inside the door.

"When did Sergeant Sowerby leave?" asked Dunbar.

"About three hours ago, sir."

"What!" cried Dunbar. "Three hours ago! But I have been here myself within that time—in the Commissioner's office."

"Sergeant Sowerby left before then. I saw him go."

"But, my good fellow, he has been back again. He spoke to me on the telephone less than a quarter of an hour ago."

"Not from here, sir."

"But I say it was from here!" shouted Dunbar fiercely; "and I told him to wait for me."

"Very good, sir. Shall I make inquiries?"

"Yes. Wait a minute. Is the Commissioner here?"

"Yes, sir, I believe so. At least I have not seen him go."

"Find Sergeant Sowerby and tell him to wait here for me," snapped Dunbar.

He walked out into the bare corridor and along to the room of the Assistant Commissioner. Knocking upon the door, he opened it immediately, and entered an apartment which afforded a striking contrast to his own. For whereas the room of Inspector Dunbar was practically unfurnished, that of his superior was so filled with tables, cupboards, desks, bureaux, files, telephones, bookshelves and stacks of documents that one only discovered the Assistant Commissioner sunk deep in a padded armchair and a cloud of tobacco smoke by dint of close scrutiny. The Assistant Commissioner was small, sallow and satanic. His black moustache was very black and his eyes were of so dark a brown as to appear black also. When he smiled he revealed a row of very large white teeth, and his smile was correctly Mephistophelean. He smoked a hundred and twenty Egyptian cigarettes per diem, and the first and second fingers of either hand were coffee-coloured.

"Good-evening, Inspector," he said courteously. "You come at an opportune moment." He lighted a fresh cigarette. "I was detained here unusually late to-night or this news would not have reached us till the morning." He laid his finger upon a yellow form. "There is an unpleasant development in 'The Scorpion' case."

"So I gather, sir. That is what brought me back to the Yard."

The Assistant Commissioner glanced up sharply.

"What brought you back to the Yard?" he asked.

"The news about Max."

The assistant Commissioner leaned back in his chair. "Might I ask, Inspector," he said, "what news you have learned and how you have learned it?"

Dunbar stared uncomprehendingly.

"Sowerby 'phoned me about half an hour ago, sir. Did he do so without your instructions?"

"Most decidedly. What was his message?"

"He told me," replied Dunbar, in ever-growing amazement, "that the body brought in by the River Police last night had been identified as that of Gaston Max."

The Assistant Commissioner handed a pencilled slip to Dunbar. It read as follows:—

"Quite so. That is the really extraordinary feature of the affair. Because, you see, Inspector, I only finished decoding this message at the very moment that you knocked at my door!"

"But——"

"There is no room for a 'but,' Inspector. This confidential message from Paris reached me ten minutes ago. You know as well as I know that there is no possibility of leakage. No one has entered my room in the interval, yet you tell me that Sergeant Sowerby communicated this information to you, by telephone, half an hour ago."

Dunbar was tapping his teeth with the pencil. His amazement was too great for words.

"Had the message been a false one," continued the Commissioner, "the matter would have been resolved into a meaningless hoax, but the message having been what it was, we find ourselves face to face with no ordinary problem. Remember, Inspector, that voices on the telephone are deceptive. Sergeant Sowerby has marked vocal mannerisms——"

"Which would be fairly easy to imitate? Yes, sir—that's so."

"But it brings us no nearer to the real problems; viz., first, the sender of the message; and, second, his purpose."

There was a dull purring sound and the Assistant Commissioner raised the telephone.

"Yes. Who is it that wishes to speak to him? Dr. Keppel Stuart? Connect with my office."

He turned again to Dunbar.

"Dr. Stuart has a matter of the utmost urgency to communicate, Inspector. It was at the house of Dr. Stuart, I take it, that you received the unexplained message?"

"It was—yes."

"Did you submit to Dr. Stuart the broken gold ornament?"

"Yes. It's a scorpion's tail."

"Ah!" The Assistant Commissioner smiled satanically and lighted a fresh cigarette. "And is Dr. Stuart agreeable to placing his unusual knowledge at our disposal for the purposes of this case?"

He stood silent for a while, listening to the voice over the wires. Then: "You want me to come around now, doctor? Very well. I'll be with you in less than half an hour."

He put down the instrument.

"Something extraordinary seems to have taken place at Dr. Stuart's house a few minutes after I left, sir," he said. "I'm going back there, now, for particulars. It sounds as though the 'phone message might have been intended to get me away." He stared down at the pencilled slip which the Assistant Commissioner had handed him, but stared vacantly, and: "Do you mind if I call someone up, sir?" he asked. "It should be done at once."

"Call by all means, Inspector."

Dunbar again took up the telephone.

"Battersea 0996," he said, and stood waiting. Then:

"Is that Battersea 0996?" he asked. "Is Dr. Stuart there? He is speaking? Oh, this is Inspector Dunbar. You called me up here at the Yard a few moments ago, did you not? Correct, doctor; that's all I wanted to know. I am coming now."

"Good," said the Assistant Commissioner, nodding his approval. "You will have to check 'phone messages in that way until you have run your mimic to earth, Inspector. I don't believe for a moment that it was Sergeant Sowerby who rang you up at Dr. Stuart's."

"Neither do I," said Dunbar grimly. "But I begin to have a glimmer of a notion who it was. I'll be saying good-night, sir. Dr. Stuart seems to have something very important to tell me."

As a mere matter of form he waited for the report of the constable who had gone in quest of Sowerby, but it merely confirmed the fact that Sowerby had left Scotland Yard over three hours earlier. Dunbar summoned a taxicab and proceeded to the house of Dr. Stuart.

CHAPTER VII

CONTENTS OF THE SEALED ENVELOPE

Stuart personally admitted Dunbar, and once more the Inspector found himself in the armchair in the study. The fire was almost out and the room seemed to be chilly. Stuart was labouring under the influence of suppressed excitement and was pacing restlessly up and down the floor.

"Inspector," he began, "I find it difficult to tell you the facts which have recently come to my knowledge bearing upon this most mysterious 'Scorpion' case. I clearly perceive, now, that without being aware of the fact I have nevertheless been concerned in the case for at least a week."

Dunbar stared surprisedly, but offered no comment.

"A fortnight ago," Stuart continued, "I found myself in the neighbourhood of the West India Docks. I had been spending the evening with a very old friend, chief officer of a liner in dock. I had intended to leave the ship at about ten o'clock and to walk to the railway station, but, as it fell out, the party did not break up until after midnight. Declining the offer of a berth on board, I came ashore determined to make my way home by tram and afoot. I should probably have done so and have been spared—much; but rain began to fall suddenly and I found myself, foolishly unprovided with a top-coat, in those grey East End streets without hope of getting a lift.

"It was just as I was crossing Limehouse Causeway that I observed, to my astonishment, the head-lamps of a cab or car shining out from a dark and forbidding thoroughfare which led down to the river. The sight was so utterly unexpected that I paused, looking through the rainy mist in the direction of the stationary vehicle. I was still unable to make out if it were a cab or a car, and accordingly I walked along to where it stood and found that it was a taxicab and apparently for hire.

"'Are you disengaged?' I said to the man. "'Well, sir, I suppose I am,' was his curious reply. 'Where do you want to go?'

"I gave him this address and he drove me home. On arriving, so grateful did I feel that I took pity upon the man, for it had settled down into a brute of a night, and asked him to come in and take a glass of grog. He was only too glad to do so. He turned out to be quite an intelligent sort of fellow, and we chatted together for ten minutes or so.

"I had forgotten all about him when, I believe on the following night, he reappeared in the character of a patient. He had a badly damaged skull, and I gathered that he had had an accident with his cab and had been pitched out into the road.

"When I had fixed him up, he asked me to do him a small favour. From inside his tunic he pulled out a long stiff envelope, bearing no address but the number 30 in big red letters. It was secured at both ends with black wax bearing the imprint of a curious and complicated seal.

"'A gentleman left this behind in the cab today, sir,' said the man—'perhaps the one who was with me when I had the spill, and I've got no means of tracing him; but he may be able to trace me if he happened to notice my number, or he may advertise. It evidently contains something valuable.'

"'Then why not take it to Scotland Yard?' I asked. 'Isn't that the proper course?'

"'It is,' he admitted; 'but here's the point: if the owner reclaims it from Scotland Yard he's less likely to dub up handsome than if he gets it direct from me!'

"I laughed at that, for the soundness of the argument was beyond dispute. 'But what on earth do you want to leave it with me for?' I asked."

"'Self-protection,' was the reply. 'They can't say I meant to pinch it! Whereas, directly there's any inquiry I can come and collect it and get the reward; and your word will back me up if any questions are asked; that's if you don't mind, sir.'

"I told him I didn't mind in the least, and accordingly I sealed the envelope in a yet larger one which I addressed to the Lost Property Office and put into a private drawer of my bureau. 'You will have no objection,' I said, 'to this being posted if it isn't reclaimed within a reasonable time?'

"He said that would be all right and departed—since which moment I have not set eyes upon him. I now come to the sequel, or what I have just recognized to be the sequel."

Stuart's agitation grew more marked and it was only by dint of a palpable effort that he forced himself to resume.

"On the evening of the following day a lady called professionally. She was young, pretty, and dressed with extraordinary elegance. My housekeeper admitted her, as I was out at the time but momentarily expected. She awaited my return here, in this room. She came again two days later. The name she gave was an odd one: Mademoiselle Dorian. There is her card,"—Stuart opened a drawer and laid a visiting-card before Dunbar—"no initials and no address. She travelled in a large and handsome car. That is to say, according to my housekeeper's account it is a large and handsome car. I personally, have had but an imperfect glimpse of it. It does not await her in front of the house, for some reason, but just around the corner in the side turning. Beyond wondering why Mademoiselle Dorian had selected me as her medical advisor I had detected nothing suspicious in her behaviour up to the time of which I am about to speak.

"Last night there was a singular development, and to-night matters came to a head."

Thereupon Stuart related as briefly as possible the mysterious episode of the cowled man, and finally gave an account of the last visit of Mlle. Dorian. Inspector Dunbar did not interrupt him, but listened attentively to the singular story.

Dunbar took it up eagerly. A small hole had been burned in one end of the envelope and much of the surrounding paper was charred. The wax with which Stuart had sealed it had lain uppermost, and although it had been partly melted, the mark of his signet-ring was still discernible upon it. Dunbar stood staring at it.

"In the circumstances, Inspector, I think you would be justified in opening both envelopes," said Stuart.

"I am inclined to agree. But let me just be clear on one or two points." He took out the bulging note-book and also a fountain-pen with which he prepared to make entries. "About this cabman, now. You didn't by any chance note the number of his cab?"

"I did not."

"What build of man was he?"

"Over medium height and muscular. Somewhat inclined to flesh and past his youth, but active all the same."

"Dark or fair?"

"Dark and streaked with grey. I noted this particularly in dressing his skull. He wore his hair cropped close to the scalp. He had a short beard and moustache and heavily marked eyebrows. He seemed to be very short-sighted and kept his eyes so screwed up that it was impossible to detect their colour, by night at any rate."

"What sort of wound had he on his skull?"

"A short ugly gash. He had caught his head on the footboard in falling. I may add that on the occasion of his professional visit his breath smelled strongly of spirits, and I rather suspected that his accident might have been traceable to his condition."

"But he wasn't actually drunk?"

"By no means. He was perfectly sober, but he had recently been drinking—possibly because his fall had shaken him, of course."

"His hands?"

"Small and very muscular. Quite steady. Also very dirty."

"What part of the country should you say he hailed from?"

"London. He had a marked cockney accent."

"What make of cab was it?"

"I couldn't say."

"An old cab?"

"Yes. The fittings were dilapidated, I remember, and the cab had a very musty smell."

"Ah," said Dunbar, making several notes. "And now—the lady: about what would be her age?"

"Difficult to say, Inspector. She had Eastern blood and may have been much younger than she appeared to be. Judged from a European standpoint and from her appearance and manner of dress, she might be about twenty-three or twenty-four."

"Complexion?"

"Wonderful. Fresh as a flower."

"Eyes?"

"Dark. They looked black at night."

"Hair?"

"Brown and 'fuzzy' with copper tints."

"Tall?"

"No; slight but beautifully shaped."

"Now—from her accent what should you judge her nationality to be?"

Stuart paced up and down the room, his head lowered in reflection, then:

"She pronounced both English and French words with an intonation which suggested familiarity with Arabic."

"Arabic? That still leaves a fairly wide field."

"It does, Inspector, but I had no means of learning more. She had certainly lived for a long time somewhere in the Near East."

"Her jewellery?"

"Some of it was European and some of it Oriental, but not characteristic of any particular country of the Orient."

"Did she use perfume?"

"Yes, but it was scarcely discernible. Jasmine—probably the Eastern preparation."

"Her ailment was imaginary?"

"I fear so."

"H'm—and now you say that Mrs. M'Gregor saw the car?"

"Yes, but she has retired."

"Her evidence will do to-morrow. We come to the man in the hood. Can you give me any kind of a description of him?"

"He appeared to be tall, but a shadow is deceptive, and his extraordinary costume would produce that effect, too. I can tell you absolutely nothing further about him. Remember, I thought I was dreaming. I could not credit my senses."

Inspector Dunbar glanced over the notes which he had made, then returning the note-book and pen to his pocket, he took up the long smoke-discoloured envelope and with a paper-knife which lay upon the table slit one end open. Inserting two fingers, he drew out the second envelope which the first enclosed. It was an ordinary commercial envelope only notable by reason of the number, 30, appearing in large red figures upon it and because it was sealed with black wax bearing a weird-looking device:

Stuart bent over him intently as he slit this envelope in turn. Again, he inserted two fingers—and brought forth the sole contents... a plain piece of cardboard, roughly rectangular and obviously cut in haste from the lid of a common cardboard box!

CHAPTER VIII

THE ASSISTANT COMMISSIONER'S THEORY

On the following morning Inspector Dunbar, having questioned Mrs. M'Gregor respecting the car in which Mlle. Dorian had visited the house and having elicited no other evidence than that it was "a fine luxurious concern," the Inspector and Dr. Stuart prepared to set out upon gruesome business. Mrs. M'Gregor was very favourably impressed with the Inspector. "A grand, pairsonable body," she confided to Stuart. "He'd look bonny in the kilt."

To an East-End mortuary the cab bore them, and they were led by a constable in attendance to a stone-paved, ill-lighted apartment in which a swathed form lay upon a long deal table. The spectacle presented, when the covering was removed, was one to have shocked less hardened nerves than those of Stuart and Dunbar; but the duties of a police officer, like those of a medical man, not infrequently necessitate such inspections. The two bent over the tragic flotsam of the Thames unmoved and critical.

"H'm," said Stuart—"he's about the build, certainly. Hair iron-grey and close cropped and he seems to have worn a beard. Now, let us see."

He bent, making a close inspection of the skull; then turned and shook his head.

"No, Inspector," he said definitely. "This is not the cabman. There is no wound corresponding to the one which I dressed."

"You were wrong, Inspector. It was not Gaston Max who left the envelope with me."

"No," mused Dunbar, "so it seems."

"Your theory that Max, jealously working alone, had left particulars of his inquiries, and clues, in my hands, knowing that they would reach Scotland Yard in the event of his death, surely collapsed when the envelope proved to contain nothing but a bit of cardboard?"

"Yes—I suppose it did. But it sounded so much like Max's round-about methods. Anyway I wanted to make sure that the dead man from Hanover Hole and your mysterious cabman were not one and the same."

Stuart entertained a lively suspicion that Inspector Dunbar was keeping something up his sleeve, but with this very proper reticence he had no quarrel, and followed by the constable, who relocked the mortuary behind them, they came out into the yard where the cab waited which was to take them to Scotland Yard. Dunbar, standing with one foot upon the step of the cab, turned to the constable.

"Has anyone else viewed the body?" he asked.

"No sir."

"No one is to be allowed to do so—you understand?—no one, unless he has written permission from the Commissioner."

"Very good, sir."

Half an hour later they arrived at New Scotland Yard and went up to Dunbar's room. A thick-set, florid man of genial appearance, having a dark moustache, a breezy manner and a head of hair resembling a very hard-worked blacking-brush, awaited them. This was Detective-Sargeant Sowerby with whom Stuart was already acquainted.

"Good-morning, Sergeant Sowerby," he said.

"Good-morning, sir. I hear that someone was pulling your leg last night."

"What do you mean exactly, Sowerby?" inquired Dunbar, fixing his fierce eyes upon his subordinate.

Sergeant Sowerby exhibited confusion.

"I mean nothing offensive, Inspector. I was referring to the joker who gave so good an imitation of my voice that even you were deceived."

"Ah," replied Dunbar—"I see. Yes—he did it well. He spoke just like you. I could hardly make out a word he said."

With this Caledonian shaft and a side-glance at Stuart, Inspector Dunbar sat down at the table.

"Here's Dr. Stuart's description of the missing cabman," he continued, taking out his note-book. "Dr. Stuart has viewed the body and it is not the man. You had better take a proper copy of this."

"Then the cabman wasn't Max?" cried Sowerby eagerly. "I thought not."

"I believe you told me so before," said Dunbar sourly. "I also seem to recall that you thought a scorpion's tail was a Prickly Pear. However—here, on the page numbered twenty-six, is a description of the woman known as Mlle. Dorian. It should be a fairly easy matter to trace the car through the usual channels, and she ought to be easy to find, too."

He glanced at his watch. Stuart was standing by the lofty window looking out across the Embankment.

"Ten o'clock," said Dunbar. "The Commissioner will be expecting us."

"I am ready," responded Stuart.

Leaving Sergeant Sowerby seated at the table studying the note-book, Stuart and Dunbar proceeded to the smoke-laden room of the Assistant Commissioner. The great man, suavely satanic, greeted Stuart with that polished courtesy for which he was notable.

"You have been of inestimable assistance to us in the past, Dr. Stuart," he said, "and I feel happy to know that we are to enjoy the aid of your special knowledge in the present case. Will you smoke one of my cigarettes? They are some which a friend is kind enough to supply to me direct from Cairo, and are really quite good."

"Thanks," replied Stuart. "May I ask in what direction my services are likely to prove available?"

The Commissioner lighted a fresh cigarette. Then from a heap of correspondence he selected a long report typed upon blue foolscap.

"I have here," he said, "confirmation of the telegraphic report received last night. The name of M. Gaston Max will no doubt be familiar to you?"

Stuart nodded.

"Well," continued the Commissioner, "it appears that he has been engaged in England for the past month endeavouring to trace the connection which he claims to exist between the sudden deaths of various notable people, recently—a list is appended—and some person or organisation represented by, or associated with, a scorpion. His personal theory not being available—poor fellow, you have heard of his tragic death—I have this morning consulted such particulars as I could obtain respecting these cases. If they were really cases of assassination, some obscure poison was the only mode of death that could possibly have been employed. Do you follow me?"

"Perfectly."

"Now, the death of Gaston Max under circumstances not yet explained, would seem to indicate that his theory was a sound one. In other words, I am disposed to believe that he himself represents the most recent outrage of what we will call 'The Scorpion.' Even at the time that the body of the man found by the River Police had not been identified, the presence upon his person of a fragment of gold strongly resembling the tail of a scorpion prompted me to instruct Inspector Dunbar to consult you. I had determined upon a certain course. The identification of the dead man with Gaston Max merely strengthens my determination and enhances the likelihood of my idea being a sound one."

He flicked the ash from his cigarette and resumed:

"Without mentioning names, the experts consulted in the other cases which—according to the late Gaston Max—were victims of 'The Scorpion,' do not seem to have justified their titles. I am arranging that you shall be present at the autopsy upon the body of Gaston Max. And now, permit me to ask you a question: are you acquainted with any poison which would produce the symptoms noted in the case of Sir Frank Narcombe, for instance?"

Stuart shook his head slowly.

"All that I know of the case," he said, "is that he was taken suddenly ill in the foyer of a West-End theatre, immediately removed to his house in Half Moon Street, and died shortly afterward. Can you give me copies of the specialists' reports and other particulars? I may then be able to form an opinion."

"I will get them for you," replied the Commissioner, the exact nature of whose theory was by no means evident to Stuart. He opened a drawer. "I have here," he continued, "the piece of cardboard and the envelope left with you by the missing cab-man. Do you think there is any possibility of invisible writing?"

"None," said Stuart confidently. "I have tested in three or four places as you will see by the spots, but my experiments will in no way interfere with those which no doubt your own people will want to make. I have also submitted both surfaces to a microscopic examination. I am prepared to state definitely that there is no writing upon the cardboard, and except for the number, 30, none upon the envelope."

"It is only reasonable to suppose," continued the Commissioner, "that the telephone message which led Inspector Dunbar to leave your house last night was originated by that unseen intelligence against which we find ourselves pitted. In the first place, no one in London, myself and, presumably, 'The Scorpion' excepted, knew at that time that M. Gaston Max was in England or that M. Gaston Max was dead. I say, presumably 'The Scorpion' because it is fair to assume that the person whom Max pursued was responsible for his death.

"Of course"—the Commissioner reached for the box of cigarettes—"were it not for the telephone message, we should be unjustified in assuming that Mlle. Dorian and this"—he laid his finger upon the piece of cardboard—"had any connection with the case of M. Max. But the message was so obviously designed to facilitate the purloining of the sealed envelope and so obviously emanated from one already aware of the murder of M. Max, that the sender is identified at once with— 'The Scorpion.'"

The Assistant Commissioner complacently lighted a fresh cigarette.

"Finally," he said, "the mode of death in the case of M. Max may not have been the same as in the other cases. Therefore, Dr. Stuart"—he paused impressively—"if you fail to detect anything suspicious at the post mortem examination I propose to apply to the Home Secretary for power to exhume the body of the late Sir Frank Narcombe!"

Deep in reflection, Stuart walked alone along the Embankment. The full facts contained in the report from Paris the Commissioner had not divulged, but Stuart concluded that this sudden activity was directly due, not to the death of M. Max, but to the fact that he (Max) had left behind him some more or less tangible clue. Stuart fully recognized that the Commissioner had accorded him an opportunity to establish his reputation—or to wreck it.

Yet, upon closer consideration, it became apparent that it was to Fate and not to the Commissioner that he was indebted. Strictly speaking, his association with the matter dated from the night of his meeting with the mysterious cabman in West India Dock road. Or had the curtain first been lifted upon this occult drama that evening, five years ago, as the setting sun reddened the waters of the Imperial Canal and a veiled figure passed him on the Wu-Men Bridge?

"Shut your eyes tightly, master—the Scorpion is coming!"

He seemed to hear the boy's words now, as he passed along the Embankment; he seemed to see again the tall figure. And suddenly he stopped, stood still and stared with unseeing eyes across the muddy waters of the Thames. He was thinking of the cowled man who had stood behind the curtains in his study—of that figure so wildly bizarre that even now he could scarcely believe that he had ever actually seen it. He walked on.

Automatically his reflections led him to Mlle. Dorian, and he remembered that even as he paced along there beside the river the wonderful mechanism of New Scotland Yard was in motion, its many tentacles seeking—seeking tirelessly—for the girl, whose dark eyes haunted his sleeping and waking hours. He was responsible, and if she were arrested he would be called upon to identify her. He condemned himself bitterly.

After all, what crime had she committed? She had tried to purloin a letter—which did not belong to Stuart in the first place. And she had failed. Now—the police were looking for her. His reflections took a new form.

What of Gaston Max, foremost criminologist in Europe, who now lay dead and mutilated in an East-End mortuary? The telephone message which had summoned Dunbar away had been too opportune to be regarded as a mere coincidence. Mlle. Dorian was, therefore, an accomplice of a murderer.

Stuart sighed. He would have given much—more than he was prepared to admit to himself—to have known her to be guiltless.

The identity of the missing cabman now engaged his mind. It was quite possible, of course, that the man had actually found the envelope in his cab a was in no other way concerned in the matter. But how had Mlle. Dorian, or the person instructing her, traced the envelope to his study? And why, if they could establish a claim to it, had they preferred to attempt to steal it? Finally, why all this disturbance about a blank piece of cardboard?

A mental picture of the envelope arose before him, the number, 30, written upon it and the two black seals securing the lapels. He paused again in his walk. His reflections had led him to a second definite point and he fumbled in his waistcoat pocket for a time, seeking a certain brass coin about the size of a halfpenny, having a square hole in the middle and peculiar characters engraved around the square, one on each of the four sides.

He failed to find the coin in his pocket, however, but he walked briskly up a side street until he came to the entrance to a tube station. Entering a public telephone call-box, he asked for the number, City 400. Being put through and having deposited the necessary fee in the box:

"Is that the Commissioner's Office, New Scotland Yard?" he asked. "Yes! My name is Dr. Keppel Stuart. If Inspector Dunbar is there, would you kindly allow me to speak to him."

There was a short interval, then:

"Hullo!" came—"is that Dr. Stuart?"

"Yes. That you, Inspector? I have just remembered something which I should have observed in the first place if I had been really wide-awake. The envelope—you know the one I mean?—the one bearing the number, 30, has been sealed with a Chinese coin, known as cash. I have just recognized the fact and thought it wise to let you know at once."

"Are you sure?" asked Dunbar.

"Certain. If you care to call at my place later to-day I can show you some cash. Bring the envelope with you and you will see that the coins correspond to the impression in the wax. The inscriptions vary in different provinces, but the form of all cash is the same."

"Very good. Thanks for letting me know at once. It seems to establish a link with China, don't you think?"

"It does, but it merely adds to the mystery."

Coming out of the call-box, Stuart proceeded home, but made one or two professional visits before he actually returned to the house. He now remembered having left his particular cash piece (which he usually carried) in his dispensary, which satisfactorily accounted for his failure to find the coin in his waistcoat pocket. He had broken the cork of a flask, and in the absence of another of correct size had manufactured a temporary stopper with a small cork to the top of which he had fixed the Chinese coin with a drawing-pin. His purpose served he had left the extemporised stopper lying somewhere in the dispensary.

Stuart's dispensary was merely a curtained recess at one end of the waiting-room and shortly after entering the house he had occasion to visit it. Lying upon a shelf among flasks and bottles was the Chinese coin with the cork still attached. He took it up in order to study the inscription. Then:

"Have I cultivated somnambulism!" he muttered.

Fragments of black sealing-wax adhered to the coin!

Incredulous and half fearful he peered at it closely. He remembered that the impression upon the wax sealing the mysterious envelope had had a circular depression in the centre. It had been made by the head of the drawing-pin!

He found himself staring at the shelf immediately above that upon which the coin had lain. A stick of black sealing-wax used for sealing medicine was thrust in beside a bundle of long envelopes in which he was accustomed to post his Infirmary reports!

One hand raised to his head, Stuart stood endeavouring to marshal his ideas into some sane order. Then, knowing what he should find, he raised the green baize curtain hanging from the lower shelf, which concealed a sort of cupboard containing miscellaneous stores and not a little rubbish, including a number of empty cardboard boxes.

A rectangular strip had been roughly cut from the lid of the topmost box!

The mysterious envelope and its contents, the wax and the seal—all had come from his own dispensary!

CHAPTER IX

THE CHINESE COIN

Deep in reflection, Stuart walked alone along the Embankment. The full facts contained in the report form Paris the Commissioner had not divulged, but Stuart concluded that this sudden activity was directly due, not to the death of M. Max, but to the fact that he (Max) had left behind him some more or less tangible clue. Stuart fully recognized that the Commissioner had accorded him an opportunity to establish his reputation—or to wreck it.

Yet, upon closer consideration, it became apparent that it was to Fate and not to the Commissioner that he was indebted. Strictly speaking, his association with the matter dated from the night of his meeting with the mysterious cabman in West India Dock Road. Or had the curtain first been lifted upon this occult drama that evening, five years ago, as the setting sun reddened the waters of the Imperial Canal and a veiled figure passed him on the Wu-Men Bridge?